Catalytic conversion



Mam-120,' i945. M. H. ARvEsoN CATALYTIC CONVERSION Filed Nov.` 24, 1941Patented Mar. 20, 1945 ,l

UNITED sTATEs PATENT oi-#FICE- Maurice H. Arveson, Flossmoor,lll.,'assignor to Standard Oil Company,

' aan or manna Chicago, Ill., a corpora- Application November 24, 1941,Serial No. 420,203 claims.' (ci. 19e-5o) This invention relates toprocesses for the catalytic conversion of hydrocarbon oils and par- Aticularly to anew method for catalytically convertingsuch materials inthe presence ofv hydro- A gasoline boiling point range to producegasolines of improved octane number. This type of process, which I willrefer to hereinafter'A as a hydro-` I will refer to these latter typesof reactions under the name of dehydrogenation reactions since all ofthe various processes referred to involve dehydrogenation. Thus,brieily, one of my catalysts is a cracking catalyst which is adapted toaccomplish the scission of. carbon to carbon bonds while the second is adehydrogenation catalyst, the action of which is reasonably specic tothe scission of carbon to hydrogen bonds.

genation process, involves the conversion of parailinic hydrocarbons,and in' some cases oleiinic and naphthenic hydrocarbons, boilinggwhollyor largely in-the gasoline boiling point range, vand l particularly inthe upper of the gasoline boiling point range, to gasoline rangehydrocarbons hamving very high octane numbers. The octane' num# ber isthe "result of the conversion of the other type of hydrocarbons,particularly the param-nic hydrocarbonsl tol aromatic hydrocarbons ofextremely good antiknock qualities.

While such processes have been very successfully applied to operationsin which a fixed bed ofcatalyst is used, it hasbeen impossible, prior tomy invention, to apply the use of suspended powdered catalysts to .suchprocesses.

. 'I'he failure of the prior art to accomplish this is apparently dueprimarily to a 4failure to appreciate the necessity of using low space velocities and also to a failure to provide high ratios of catalyst tooill in the reactor.

It is an object of my invention to provide'a particularly advantageousreforming, aromatiza tion or dehydrogenation process of the type inwhich a cataLvst is suspended in the vapors un.-

dergolng conversion. Still another object of nu' invention is to providea catalytic conversion Yprocess of the powdered catalyst type in whichthe catalyst is used with maximum eiilciency. It

groups IV, V and VI of the periodic table. Sul- In employing a mixedcatalyst of this type,`

charging stocks having a substantial quantity of hydrocarbons boilingabove the gasoline boiling point range as well as a substantial quantityboiling within the gasoline boiling point range can suitably beemployed. i

However, I prefer to employ, in place .of a'.

mixture of two catalysts, -a powdered catalyst, the action of which issubstantialhr solely directed to dehydrogenation reactions, notably ofthe dehydroaromatization type, and in this case the suitable chargingstock is one boiling at least' predominantly in the upper portion of thegasoline boiling point range, for instance within'the approximate rangefrom 200 to 450 F.

Catalysts which are particularly adapted to this reaction are themetals, z or preferably the oxides ofmetals, from the lefthand columnsof iides of these same metals can also be used but is also an object ofmy invention to produce good yields of high antikncck gasoline. Otherand more detailed objects, advantages and uses of my invention willbecome apparent as the de1 scription thereof proceeds.

In connection with my invention I can employ l a powdered catalyst whichis a mixture of two catalysts. one ot which is primarily a crackingcatalyst-for instance, valumina on silica-and are definitely lessdesirable. Particularly good results are given by the oxides of chromiumand molybdenum. While these oxides of metals from the left hand columnsoi groups IV, V and VI or the corresponding metals themselves can beused lalone -or on any desired supporting material, it is particularlyeilicacious to use them supported on alumina. Any form `of alumina canbe used but activated alumina gives particularly good results andaluminagel gives in general still better results. Thus a dehydrogenationcatalyst canbe made by digesting an alumina gel in a solution of amolybdenum salt followed by filtration, washing and drying' at anelevated temperature. T

Theioxide or oxides, for instance alumina or v molybdena adsorbed on thealumina support, can

be present in various amounts ,but in general the active oxide or oxides(or the metal or metals) should be from 1 to 30% by weight or the totalcatalyst including the support, for instance 10%.

As an example'of my process I refer to 'the accompanying drawing whichillustrates one embodiment of my invention. In the drawing Fig- Yure 1vis a 'simplied `iiow diagram illustrating a process in accordance withmy invention and Fig- Turning now to Figure 1, a petroleum or otherhydrocarbon charging stock, for instance a heavy hydrocarbons (by meansnot shown) Aand passed by pump 23 to catalyst regeneration system 21naphtha boiling predominantlyvwithin the range from 200 to 450 F. andpreferably a virgin stockor other stock rich in paratlln hydrocarbons',is

pumped from feed tank l through valved line I l by means ofpump I 2. Thepowdered catalyst can be injected in a slurry form into the charge goingto coil I3 by means of valved line il and pump IE. However, it ispreferred to vaporize the charge in coil I3 before injecting thecatalyst, and in this preferred operation the powdered cat alyst ormixed powdered catalysts are injected into the vapor stream by means ofvalved line i8. If slurry catalysts are used, the liquid in which thecatalyst is suspended (for instance a portion of the charge) isvaporized'bythe time it passes through coil la, and thus with eitherslurry injection or powder injection the catalyst passes through coil ilin powdered form suspended in the vapors to be converted.

Coil i3 can be arranged in a re1atively cool portion of furnace I3 andcoil I1 in the radiant section as shown.

The conversion products along with the catalyst passes through transferline I9 to separator 20, which maysuitably be of the cyclone type, wherea large portion, for instance 70 to 98% of the catalyst,'is separatedout and recycled via line 2 I, pump 22 and catalyst storage and handlingchamber 23. By recycling a part, preferably a large part, of thepowdered catalyst the size of the regeneration system and the expense ofregeneration are greatly reduced. and it is. possible to increase verymarkedly the economically usable4 siderably higher. This total catalystto oil ratio' A is, in terms of the apparatus of Figure 1, the totalweight of catalysts (fresh, recycled, regenerated) charged to thecontacting step in unit time divided by the weight of total chargingstock I charged to\the contacting step in the same time,

in other words it is the catalyst to oil ratio in the reaction zone.

My combination of a large proportion of cat-y alyst recycled within thesystem, without regeneration, and a very high total catalyst to oilratio in the reaction zone, for instance `from 5:1 to :1 or higher,isparticularly advantageous' in the dehydrogenation ordehydro-'aromatization of heavy naphthas as above described. Stillhigher catalyst to oil ratios up to whatever maximum can be attainedwith the equipment used are likewise advantageous. Thus with an upflowreactor of the type now well known .to the art in which the hydrocarbonvapors pass upward through the reaction zone at a low linear velocity tosuspend the powdered catalyst'in a Huid bed of high density, thecatalyst to oil ratio in the reaction zone, on a weight basis can be50:1, 100:1 or higher. v

which can be offany desired type and in which the catalyst can beregenerated by treatment with hydrogen at high temperatures andpressures or with solvents or by any other means but Preferably byblowing with air or other oxygen-containing ges, to remove carbonaceousdeposits.

This air can be injected through line 23 and the resulting flue gas canbe withdrawn through line 23. The regenerated catalyst 'is conveyedthrough line 30 to catalyst storage and handling chamber 23.

Further adjustment of the relative amounts of catalysts recycled withand without regeneration can be accomplished by means of valved line 3|.Fresh make-up catalyst can be added through line 3la by pump 3lb from as ource not shown.

.Turning to Figure 2 I have illustrated one possibleiform ofregeneration system in more detail.

The catalyst from separator 25 passes through Returning to Figure 1. thevapors from separator 2 0 carrying a minor part of the catalyst passthrough line 24 to a second separator 25 in which substantially all ofthe remainder of the catalyst is separated out, steamed to remove.adsorbed stripper 32 where it is stripped with an inert gas introducedthrough line 33, and then through a series of elongated revivificationchambers 36,35"

and 36. Air diluted from nue gas enters the nrst reviviilcation chamber34 through valved line 31 along with the catalysts and additional airand flue gas can be injected by valved lines 38 and 39 into thesubsequent reviviflcation chambers 35 and 38, or air alone can beintroduced into the latter chambers by the use of valved line 33a, valve33h being closed, in order to accomplish complete oxidation ofthecarbonaceous material without overheating the catalyst in the firstreviviiication chamber 34. Chambers 34, 36 and 33 can be cooled by acooling medium introduced through line d0 and removed through lines 4Ito prevent overheating the catalysts during revivi-V fication. Therevivifled or regenerated catalyst along with the gases pass toseparator 42 which may be of the cyclone type and the gases arediscarded through flue 29. The catalyst is then conveyed through line 30to catalyst storage and handling chamberr 23.

It may be well to mention at this point that the diagrammatic showing ofFigures 1 and 2 omits many features which those skilled in the art wouldrecognize as desirable or essential in actual plant operation. Theseomissions are made in order to simplify the presentation of theinvention and to avoid encumbering it with well understood engineeringdetails. fIhus, for example, catalyst conveying and handling systems arenot shown in detail, gas locks between the conversion system and theregeneration system are not provided and various desirable flow control,pumping, heat exchange andsafety equipment is-omitted from thediagrammatic representation.

Reverting now to Figure l conversion products pass from separator 25'through. line -43 to fractionator Il. In this fractionator, which ispreferably operated under rather high pressure, a roughsseparationbetween gasoline and gas is made. The liquid from this fractionating co1umn is passed to a second fractionator I5 where material boiling abovethe gasoline boiling point range is separated as a bottoms and withdrawnthrough valved line 46. This material which may 'be called cycle gas oilor polymer can be recycled With the feed or, preferably, Withdrawn fromthe system for thermal conversion or other use. The gasoline product istaken overhead from charge be preheated in coil I3 to about re- I actiontemperature.

My `process can be operated at atmospheric pressure or at aT slightlyelevated pressure, for

e5 by means oi' pump 54 and valved line 55 as reflux and the remainderbeing pumped by pump --54 through valved line 56 to stabilizer 51, fromthe bottomk of which the high octane number gasoline product iswithdrawn through valved line 58. The light hydrocarbon gases fromstabilizer 51 pass through condenser 59 and line ySil to separator 6|from which iixed gases' are removed from the system through valved line5 2, while the condensables are in part removed through valved line 83and in part recycled as'reux to stabilizer- 51 by means of pump 54 andvalved line 55.

I have described how the liquid fraction from fractionator -44 iscarried through to the finished gasoline. However, since this irstfractionator makes only a rough separation between gas and gasoline, theoverhead which is removed through line 5S and condenser 51 containsconsiderable gasoline as well as other condensables, and these areseparated from, gas in separator 58 and sent to stabilizer 51 throughline 59 by pump 10. The gases from this separator which are very rich inhydrogen pass through valved line 1I for recycling. Gas holder 52 iloatson the recycle line.

However, since my process produces hydrogen .rather than consuming it, aportion o`f this gas must be removed from the system through .valved lline 12 when the capacity of the gas holder is exceeded. l

Hydrogen is added to the feed by means of compressor 'I3-in line 14.This hydrogen' (being that produced by the process) inevitably containsconsiderable amounts of methane and other light hydrocarbons as' well asother impurities. While this impure hydrogen can be sent directly intothe conversion coil I 3 via line 1I, valved by-pass -line` 15 and line15, it can alternatively be sent, in whole or in part, through apurication system 11 (shown diagrammatically) from which impurities areremoved via line `'18. This purication system may involve absorption,gascracking, and/or other steps, but does not constitute an importantfeature of the present invention and will therefore not be described indetail.

Movement of catalyst in lines I4 and/or `|5 can be -aided byintroduction of gas from line 15 through valved line i8 to the dischargeline from pump i5. This gas may be. and preferably is', preheated bypreheater 80 which may be a coil in furnace I8 or in a separatefurnace.A If de'-Y sired all hydrogen-containing gas may be introducedby this route.Y l

By thus converting the charging stock in the a presence of addedhydrogen. much larger yields of the valuable aromatic hydrocarbons canbe Vobtained and the catalyst does not deteriorate as readily or requireregeneration as often as'it otherwise would. However, in my powderedcata? lyst system the added hydrogen-has another very Y importantadvantage; namely, it increases' the p vapor volume and vapor velocityto a point which permits much higher ratios oi' catalyst to charge thanwould otherwise be possible. and thus gives `instance from 30 to 450pounds per square inch.

Pressures oi 100 to `200 pounds per square inch are suitable.

As previously pointed out, I ilnd it highly desirable to use anextremely large amount of catalyst, particularly when the catalyst isrich in, or conilned to.. 'the dehydrogenation component. Thus, forinstance, excellent results are obtained by suspending in thehydrocarbon vapors mixed with hydrogen an amount ofV powdered catalystequal to from about 5 to about 20 times the weight of charging stockpresent in the mixed vapors in which the catalyst is suspended. Anydesired to 011,1 then find it highly desirable to use a cona tactingzone of such size as to give a space velocity of from 0.1 to'3 volumesoi' charging stock (measured as liquid) passing through `the contacting,

`zone per hour per apparent or net volume of catalyst present in thiscontacting zone. By apparent or net volume of the catalyst I refer tothe gross space which would be occupied by the catalyst if the catalystparticles were at rest in contact with each other as they are in a fixedbed. 'I'his preferred space velocity of from 0.1 to 3 vlurnes per volumeper hour is applicable not only to my preferred powdered catalysttechnique but also to ilxed bed and moving granular bed work. As anexample a -space velocity of 1.4 is suitable. 1

Recycle gas rich in hydrogen can be used in amounts ranging from 0.5 to10 mois per moi of l charge. This molratio is roughly the same as 4o theratio by volume of recycled gas to vaporized charge, .both beingmeasured at the same .-tem. perature. The mol ratio or vapor ratio may,for instance, be 2. t

This is a continuation-in-part of my cepending application Ser. No.294,772, illed September 13, 1939. y Having described my invention inconnection with certain specincembodiments thereof, I wish it to beunderstood that these are by way of example rather than by way oflimitation and that I do not intend to be restricted thereby but only tothe scope of the appended claims.

I claim: y l. A process i'or the conversion of' heavy naphtha into highoctane gasoline which comprises maintaining within a conversion zone anadmixture of hydrogen, naphtha vapors and a powdered hydroaromatizationcatalyst, the said catalyst being dispersed in said admixture, passingthe admixture through said conversion zone at a space velocity ofbetween about 0.1 and about 3 volumes or naphtha measured as a liquidper hour per net volume of catalyst within said conversion zone, theweight of naphtha in the conversion zone in which the catalyst isdispersed being not more than about one-nith the weight Aof Vthedispersed catalyst within the conversion-` zone, land maintaining' theconversion zone at reaction temperature and pressure.-

2. A process for the conversion of a ,hydrocarn bon charging stockcomprising substantial proportions of hydrocarbons boiling within thegaso-` line boiling point range to antiknock gasoline which 'comprisesthe steps of contacting an ad- 4 mixture of charging stock vapors, addedhydro gen and a large amount of powdereddehydrogenation catalyst withina conversion zone at an #.elevated temperature, the weightot chargingstock in the'conversion zone in which the cata lyst is dispersed beingnot more than about oneiifth the weight of the dispersed catalyst insaid zone maintaining a net flow oi the charging stock through saidconversion zone at a space velocity of between about 0.1 and about 3volumes .of

charging stock measured as' a liquid per hour per a net volume ofcatalyst within said conversion zone, continuouslyseparating out betweenabout '10% and about 98% of said catalyst. contacting additionalquantities of said charging stock with said separated catalyst withinthe said conversion zone without intermediate regeneration of saidcatalyst, separating from fthe conversion products the remainder of saidcatalyst, regenerating the last..menti'oned catalyst in a hot4 process,and contacting additionalamounts of charging stock with theregenerate'dcatalyst.

3. The process for converting hydrocarbon charging stock comprisingsubstantial proportions i025 F. within a contacting zone, passing thecharging stock vapors through said contacting zone at a space velocityofbetween about 0.1 and about 3 volumes of said charging stock measured asa liquid Der hour per net volume ot said catalyst within said contactingzone. the weight of .hydrocarbon'charging stock inthe conversion zone inwhich the catalystis contacted being not more than about one-fth of theAweight of catalyst within the conversion zone.

^ steps ot contacting an admixture of l'lydrocar powdereddehydrogenation catalyst, passing said naphtha through a conversion zoneat a space velocity of between about 0.1 and about 3 volumes voi* liquidnaphtha per hour per net volume of catalyst in said conversion zone,maintaining within the conversion`zone a concentration of .gases andvapors equal to not more than oneith the. weight of the dispersedcatalyst within the conversionzone, maintaining the conversion zone at atemperature of .between about 850 and about 1025" F. and ata pressure ofbetween about and about 450 pounds per square inch, continuouslyseparating the bulk of the suspended catalyst from the conversionproducts, contacting additional amounts of naphthawith-the said catalystwithin the conversion zone without re- Benerati'on of the catalyst,recovering. the remainder oi' said catalyst' from the conversionproducts, and regenerating the last mentioned catalyst in -a hotprocessand recycling the regenerated catalyst to the conversion zone.

5.- A process ifor the conversion of a hydrocarbon charging stockcomprising substantial proportions of hydrocarbons boiling within thegasolineboiling point range into a high octane number vgasoline whichvprocess comprises the bon charging stock. vapors, between about 0.5

and about 10 mols of added hydrogen-Prion gas per mol ofv said chargingstock. andi a powdered v dehydrogenation catalyst, .maintaining saidmixed 4. A process for the conversion of a heavy v naphtha" to highoctane number gasoline which comprises contactinganadmixture of naphthavapors, between about 0.5 and aboutv 10 mols of hydrogen-rich gasepermol of naphtha and a t catalyst.

vapors and suspendedcatalyst within a conver- -sion zone at atemperaturen: between about 850 and about 1025 F.- and at a pressure ofbetween about'30 and about 450 pounds per square inch, said hydrocarbonvapors through said conversion zone at a'space velocity o! between about0.1 and about 3 volumes of said charging "stock measured as a liquid'per hour per net lvolume of vcatalyst present in said conversion zone,-and maintaining ril. dispersion of catalyst in -mixed vapors within theconversion zone, the weight o! ch stock inthe conversion zone inwhichthe ca is dispersed being not more than about one-iitth the weightof the dispersed MURI@ H. -ARVESON.

